Allegedly, the CIA tried to pass Iranian officials doctored blueprints for a nuclear trigger (an effective trigger being one of the chief obstacles to a really ‘good’ A-bomb). The idea was to set their program back years by getting them to expend their efforts building a defective unit from sabotaged plans. Unfortunately, the Russian agent who was to pass the plans on didn’t want to look bad to his Iranian contacts, so he included an errata pointing out the mistakes.